This invention relates to a transmission system of a class IV partial response code.
It is known in the art that a class IV partial response code of the type described is given from a transmitter by encoding an input signal in accordance with a predetermined encoding rule determined therefor and is accompanied by redundancy. With such a code, it is possible to detect, in a receiver, a code error undesiredly occurring during transmission from the transmitter to the receiver. Practically, such a code error is detected in the receiver by monitoring a disturbance or violation of the encoding rule which results from the code error.
It is also known in the art that a pair of bipolar code sequences are interleaved with each other in a succession of the class IV partial response code. As to a bipolar code, recent interests have been directed to a simultaneous transmission of a main signal and subsidiary signals, such as alarm information, commands, control information, and the like. Such subsidiary signals can be transmitted by intentionally disturbing or violating an encoding rule of the bipolar code by the use of redundancy accompanying the bipolar code. This may apply to the class IV partial response code.
However, it is conventional thought that, in the class IV partial response code, detection of the code error is never compatible with the simultaneous transmission of the subsidiary signals and the main signal.
When consideration is made of a succession of a multilevel class IV partial response code carrying a plurality of data signal successions arranged in the form of blocks in the code sequence, it should be necessary to locate each of the blocks, as will later be described with reference to one of eleven figures of the accompanying drawing. For this purpose, a block synchronizing signal may be arranged in a time slot allotted to the block synchronizing signal. However, it is not preferable in a transmission rate to prepare, in the code succession, such a time slot particular to the block synchronizing signal.